The present invention relates to finish compositions for use with synthetic filaments and relates more particularly to a neat oil finish composition and synthetic filaments coated with such composition.
Known neat oil finishes typically used for polyamide and polyester yarns contain high percentages of nonionic surfactants, e.g., 30 weight percent, which provide good dissipation of electrostatic charge, filament bundle cohesion, and desirable wetting properties to the yarn. Unfortunately, such high percentages of nonionic surfactants in the finish can be disadvantageous since they generally increase the finish viscosity which makes uniform application of finish difficult. Also, nonionic surfactants increase the propensity of the finish to undergo oxidative degradation and to fume when exposed to heat. The disadvantages become particularly apparent when such finishes are used as "spin finishes" in the manufacture of high tenacity polyamide and polyester industrial yarns where high draw ratios and high temperatures are used.
The presence of nonionic surfactants in neat oil finishes can also cause problems when a yarn is to be used in woven fabrics. Nonionic surfactants are sometime incompatible with size, especially polyacrylic acid size, and thus nonionic surfactant can cause sizing, weaving, and scouring problems for fabric makers.
To improve application uniformity of high viscosity neat oil finishes containing nonionic surfactants, low molecular weight diluents like mineral spirits are sometimes added to reduce finish viscosity. However, these diluents can introduce fire and explosion hazards since they increase finish fuming and may also cause health and environmental problems. Using higher finish application temperatures to reduce viscosity is not a desirable practice with finishes containing high percentages of nonionic surfactants since increased thermal degradation will result. If it is attempted to reduce the nonionic surfactant content to a lower percentage, e.g., 5 weight percent by substitution with additional lubricant, the resulting finish provides poor electrostatic protection during yarn manufacture and in end-use processing.